How to implement a couple of PXF routines?

[Walter Spector]

Steve Kargl wrote:
> 
> On Sun, Aug 05, 2007 at 10:14:45AM -0700, Walter Spector wrote:
> >
> > 1.) PXFFILENO - Given a Fortran unit 'iunit', return the POSIX file
> > descriptor associated with that unit.  If all is well, 0 is returned
> > in ierror.  Otherwise ierror returns EINVAL (iunit is not an open unit)
> > or EBADF (iunit is not connected with a file descriptor)...
> gfortran has FNUM for compatiability with g77...

Ok, I took a look at the source.  It seems all I have to do is call
unit_to_fd to get the file descriptor.  Nice.  So PXFFILENO would look
something like:

int unit_to_fd (int fd);

void
pxffileno_ (int *iunit, int *ifildes, int *ierror)
{
    *ifildes = unit_to_fd (*iunit);
    *ierror = (*ifildes >= 0) ? 0 : EBADF;
}

(Feel free to add it to the gfortran library.)

By the POSIX spec, it would be nice to distinguish between EINVAL and EBADF.
But looking upwards into unit_to_fd and friends, it doesn't look easy enough
to be worth the effort.

Onwards to PXFFDOPEN - but not tonight.

W.